CN115244860A

CN115244860A - Antenna interface device

Info

Publication number: CN115244860A
Application number: CN202080098808.1A
Authority: CN
Inventors: F·梅斯基塔; S·安德尔松
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2020-03-20
Filing date: 2020-03-20
Publication date: 2022-10-25
Also published as: WO2021185458A1; BR112022018199A2; CA3172517A1; TW202139615A; US11855679B2; US20230102583A1; TWI753784B; JP2023518063A; EP4122107B1; CO2022013447A2; EP4122107A1

Abstract

An antenna interface apparatus for cancellation of a transmit signal at a receiver port of a transceiver is disclosed. The antenna interface apparatus includes a distributed transformer and an impedance. The distributed transformer has a primary side winding connectable to an antenna port of the transceiver and with a first portion (111) and a second portion (112), a first secondary side winding (113) connectable to a transmitter port of the transceiver and with a first inductive coupling to the first portion of the primary side winding, and a second secondary side winding (114) connectable to a receiver port of the transceiver and with a second inductive coupling to the second portion of the primary side winding. Impedances (106, 107) are connected between the first secondary side winding and the second secondary side winding. The first and second inductive couplings are adapted to provide a first version of the transmit signal at the receiver port, and the impedance is adapted to provide a second version of the transmit signal at the receiver port for cancelling the first version of the transmit signal. In some embodiments, the antenna interface device is also used for cancellation of received signals at the transmitter port of the transceiver. Corresponding transceivers and communication devices are also disclosed. In some embodiments, the antenna interface device is also used for cancellation of received signals at the transmitter port of the transceiver. Corresponding transceivers and communication devices are also disclosed.

Description

Antenna interface device

Technical Field

The present disclosure relates generally to the field of antenna interfaces for transceivers, where an antenna is shared by a transmitter and a receiver. More particularly, it relates to mitigation of signal leakage from a transmitter to a receiver.

Background

An antenna interface is typically applied to a transceiver, where the antenna is shared by the transmitter and the receiver. Sharing an antenna may result in signal leakage (also known as self-interference) from the transmitter to the receiver, for example. When the transmit signal (or a portion of the transmit signal) is leaked to the receiver, receiver performance may become worse than if the transmit signal was not leaked.

Therefore, it may be desirable to mitigate signal leakage from the transmitter to the receiver for transceivers with shared antennas. Mitigation of transmit signal leakage may be particularly desirable when transmission and reception occur simultaneously and/or at the same frequency interval; for example, when the transceiver is a full-duplex transceiver or a half-duplex transceiver.

Self-interference mitigation may be addressed by either isolation (i.e., attempting to minimize leakage) or by cancellation (i.e., attempting to subtract out leakage as seen by the receiver). Self-interference cancellation has the advantage of cancelling out transmitter impairments that are typically addressed (e.g., power amplifier non-linearities).

There are several approaches for self-interference mitigation; such as (passive or active) balanced duplexers, circulators, wilkinson combiners, impedance balancing networks, and the like. However, these solutions have drawbacks such as one or more of the following: sensitivity to antenna impedance, inherent 3dB loss, relatively large physical size, high circuit complexity, impediments when attempting integration, incompatibility with full duplex operation (simultaneous transmission and reception using the same or overlapping frequency separation).

Accordingly, there is a need for alternative and/or improved antenna interfaces that provide mitigation of signal leakage from a transmitter to a receiver.

Disclosure of Invention

It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Generally, when a device is referred to herein, it is to be understood as a physical product; such as a device. The physical product may include one or more portions of control circuitry, such as in the form of one or more controllers, one or more processors, and so forth.

Also generally, when a first feature is referred to herein as connectable to a second feature, the first feature may be configured to be connected to the second feature according to some embodiments, and the first feature may be connected to the second feature according to some embodiments.

It is an object of some embodiments to address or mitigate, alleviate or eliminate at least some of the above or other disadvantages.

A first aspect is an antenna interface apparatus for cancellation of a transmit signal at a receiver port of a transceiver. The antenna interface apparatus includes a distributed transformer and an impedance.

The distributed transformer has a primary side winding connectable to an antenna port of the transceiver and having a first portion and a second portion, a first secondary side winding connectable to a transmitter port of the transceiver and having a first inductive coupling to the first portion of the primary side winding, and a second secondary side winding connectable to a receiver port of the transceiver and having a second inductive coupling to the second portion of the primary side winding.

An impedance is connected between the first secondary side winding and the second secondary side winding.

The first inductive coupling and the second inductive coupling are adapted to provide a first version of the transmit signal at the receiver port.

The impedance is adapted to provide a second version of the transmit signal at the receiver port for cancelling the first version of the transmit signal.

In some embodiments, the antenna interface device is further for cancellation of a received signal at a transmitter port of the transceiver, wherein the first inductive coupling is further adapted to provide a first version of the received signal at the transmitter port, and wherein the second inductive coupling and the impedance are further adapted to provide a second version of the received signal at the transmitter port for cancellation of the first version of the received signal.

In some embodiments, a first end of the first portion of the primary side winding is connectable to an antenna port of a transceiver and a second end of the first portion of the primary side winding is connected to a first end of the second portion of the primary side winding, the first end of the first secondary side winding is connected to an impedance and connectable to a transmitter port of the transceiver, and the first end of the second secondary side winding is connected to an impedance and connectable to a receiver port of the transceiver.

In some embodiments, the transmitter port, the receiver port, and the antenna port are single ended. In such an embodiment, the second end of the second portion of the primary side winding, the second end of the first secondary side winding and the second end of the second secondary side winding may be connectable to a reference potential.

In some embodiments, the first inductive coupling and the second inductive coupling are non-inverting inductive couplings.

In some embodiments, the transmitter port, the receiver port, and the antenna port are differential ports having a positive terminal and a negative terminal. In such embodiments, the second end of the second portion of the primary side winding may be connectable to an antenna port of a transceiver, the second end of the first secondary side winding may be connectable to a transmitter port of the transceiver, and the second end of the second secondary side winding may be connectable to a receiver port of the transceiver.

In some embodiments. The first inductive coupling and the second inductive coupling are non-inverting inductive couplings, and the impedances include a first impedance connectable between a positive terminal of the transmitter port and a positive terminal of the receiver port and a second impedance connectable between a negative terminal of the transmitter port and a negative terminal of the receiver port.

In some embodiments, one of the first inductive coupling and the second inductive coupling is an inverting inductive coupling, the other of the first inductive coupling and the second inductive coupling is a non-inverting inductive coupling, and the impedances include a first impedance connectable between the positive terminal of the transmitter port and the negative terminal of the receiver port and a second impedance connectable between the negative terminal of the transmitter port and the positive terminal of the receiver port.

In some embodiments, the impedance includes a real-valued portion and/or an imaginary-valued portion.

In some embodiments, the impedance is adapted to compensate for defects and/or impedance mismatches of the distributed transformer.

In some embodiments, the antenna interface device further comprises one or more of: a first circuit element connected in parallel to the primary side winding, a second circuit element connected in parallel to the first secondary side winding, and a third circuit element connected in parallel to the second secondary side winding. Any of the first, second and third circuit elements may comprise real and/or imaginary value parts and may be adapted to compensate for imperfections and/or impedance mismatches of the distributed transformer.

In some embodiments, one or more of a size of the first portion of the primary side winding, a size of the second portion of the primary side winding, a size of the first secondary side winding, a size and an impedance of the second secondary side winding are selected for matching of the transmitter port impedance and/or the receiver port impedance.

In general, when referring herein to the dimensions of (a portion of) a winding, the term "dimensions" may refer to any suitable measure of the winding (e.g. one or more of the number of turns/turn of the winding, the thickness of the winding wire, the cross-sectional shape of the winding wire, a measure related to the material of the winding wire, a measure related to the core of the winding, etc.).

In some embodiments, the effect of the impedance on the amplitude of the transmit signal is equal to the combined effect of the first inductive coupling and the second inductive coupling on the amplitude of the transmit signal.

In some embodiments, the phase effect of the impedance on the transmit signal and the combined phase effect of the first inductive coupling and the second inductive coupling on the transmit signal have a modulo-2 pi phase difference equal to pi for the periodic transmit signal.

A second aspect is a transceiver comprising the antenna interface apparatus of the first aspect.

In some embodiments, the transceiver is a full-duplex transceiver or a half-duplex transceiver.

In some embodiments, the transceiver is a Time Division Duplex (TDD) transceiver.

A third aspect is a communication device comprising the antenna interface device of the first aspect and/or the transceiver of the second aspect.

In some embodiments, any of the above aspects may additionally have features that are the same as or correspond to any of the various features as explained above for any of the other aspects.

An advantage of some embodiments is that an antenna interface is provided; the antenna interface is configured to mitigate signal leakage from the transmitter to the receiver by cancellation.

An advantage of some embodiments is that an antenna interface is provided; the antenna interface is configured to mitigate signal leakage of the received signal from the antenna to the transmitter by cancellation.

An advantage of some embodiments is that an antenna interface is provided; the antenna interface is configured to provide isolation between a transmitter and a receiver.

An advantage of some embodiments is that isolation can be achieved over a relatively large bandwidth.

An advantage of some embodiments is that the antenna interface is robust against impedance variations of the transceiver port (one or more of: transmitter port impedance variations, receiver port impedance variations, and antenna port impedance variations).

An advantage of some embodiments is that the losses in the transmission path are relatively low. Optimization or at least improvement of the transmission path may benefit system efficiency.

An advantage of some embodiments is that no adjustable dummy load is required, which reduces circuit complexity compared to some prior art approaches.

An advantage of some embodiments is that perfect (or near perfect) cancellation can be obtained even with non-ideal transformers; due to that, the cancellation is achieved by the impedance.

An advantage of some embodiments is to provide an antenna interface suitable for communication standards with low power and/or full duplex requirements, such as bluetooth low energy BLE mesh networks.

Advantages of some embodiments are: sufficient performance is achievable even with non-ideal components.

An advantage of some embodiments is that they are suitable for full integration in Complementary Metal Oxide Semiconductor (CMOS) technology or any other suitable semiconductor technology.

Drawings

Further objects, features and advantages will appear from the following detailed description of embodiments, with reference to the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating example embodiments.

FIG. 1 is a schematic diagram illustrating an example apparatus according to some embodiments;

FIG. 2 is a schematic diagram illustrating an example apparatus according to some embodiments;

FIG. 3 is a schematic diagram illustrating an example apparatus according to some embodiments;

FIG. 4 is a schematic diagram illustrating an example apparatus according to some embodiments; and

fig. 5 is a schematic block diagram illustrating an example apparatus according to some embodiments.

Detailed Description

As already mentioned above, it should be emphasized that the term "comprises/comprising" (which may be substituted by "comprises/comprising") when used in this specification is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Embodiments of the present disclosure will be described and illustrated more fully hereinafter with reference to the accompanying drawings. The solutions disclosed herein may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Hereinafter, embodiments will be described in which an antenna interface device that mitigates leakage of a signal from a transmitter to a receiver and/or leakage of a reception signal from an antenna to a transmitter is provided. Mitigation is achieved by cancellation.

According to various embodiments, the transmit signal leakage may be fully or partially cancelled at the receiver. Embodiments presented herein aim to achieve cancellation of the leakage of the transmission signal by adding at the receiver a signal having the same amplitude and opposite phase (i.e. pi or 180 deg. phase difference) compared to the leaked part of the transmission signal.

According to various embodiments, receive signal leakage may be fully or partially cancelled at the transmitter. Embodiments presented herein aim to achieve cancellation of received signal leakage by adding signals at the transmitter that have the same magnitude and opposite phase (i.e. pi or 180 deg. phase difference) compared to the leaked portion of the received signal.

Some embodiments are suitable for transceivers in which the antenna is shared by the transmitter and receiver. Alternatively or additionally, some embodiments are suitable for transceivers in which transmission and reception occur simultaneously and/or at the same frequency interval; such as a Time Division Duplex (TDD) transceiver and/or a full-duplex transceiver or a half-duplex transceiver.

Some embodiments are suitable for communication devices (e.g., wireless communication devices) that include a transceiver. Example communication devices include User Equipment (UE), base Station (BS), or any other radio access node.

It should be noted that even though the antenna interface device is described herein in the context of a wireless transceiver including an antenna, the antenna interface device is equally applicable in other contexts. For example, the antenna interface device may be used with a transceiver configured for communication over a wired medium. In such an example, the portion of the antenna interface device that is connectable to the antenna port is simply connected to the non-antenna port of the transceiver.

Thus, while a portion is described herein as being connectable to an antenna port of a transceiver, it should be understood that the portion is equally connectable to a non-antenna port of the transceiver, where the non-antenna port is a port for communication medium access.

According to some embodiments, the antenna interface devices described herein may be fully integrated in Complementary Metal Oxide Semiconductor (CMOS) technology or any other suitable semiconductor technology.

The antenna interface apparatus described herein is transformer-based and may be considered an application of the passive cancellation method.

As will be apparent from the examples below, the antenna interface apparatus of some embodiments uses a signal sensed at a transmitter port of a transceiver for cancellation of transmit signal leakage to a receiver port, and impedance is used to adjust amplitude (and phase) for cancellation. Similarly, the antenna interface apparatus of some embodiments uses the signal sensed at the receiver port of the transceiver for cancellation of received signal leakage to the transmitter, and the impedance is used to adjust the amplitude (and phase) for cancellation.

FIG. 1 schematically illustrates an example apparatus according to some embodiments.

Fig. 1 illustrates an example antenna interface apparatus 100 for cancellation of a transmit signal at a receiver port of a transceiver. Example connections of the antenna interface apparatus to the Transmitter (TX) 101, receiver (RX) 104 and Antenna (ANT) 103 of the transceiver are also shown.

The antenna interface device 100 includes an impedance (illustrated as two

resistors

106, 107 in fig. 1) and a distributed transformer. The distributed transformer has a primary side winding with a first portion 111 and a second portion 112, a first secondary side winding 113 and a second secondary side winding 114. The first secondary side winding 113 has a first inductive coupling 133 to the first part 111 of the primary side winding and the second secondary side winding 114 has a second inductive coupling 134 to the second part 112 of the primary side winding.

In the transceiver illustrated in fig. 1, the transmitter port, the receiver port, and the antenna port are differential ports having a positive terminal and a negative terminal.

The first end of the first portion of primary side windings 111 may be connected to one of the terminals 191 of the antenna port of the transceiver (terminal "+" in this example), the second end of the first portion of primary side windings 111 is connected to the first end of the second portion of primary side windings 112, and the second end of the second portion of primary side windings 112 may be connected to the other of the terminals 192 of the antenna port of the transceiver (terminal "-" in this example).

A first end of the first secondary side winding 113 may be connected to one of the terminals 193 (terminal "+" in this example) of the transmitter port of the transceiver, and a second end of the first secondary side winding 113 may be connected to the other of the terminals 194 (terminal "-" in this example) of the transmitter port of the transceiver.

The first end of the second secondary side winding 114 may be connected to one terminal 195 (terminal "+" in this example) of the terminals of the transceiver's receiver port, and the second end of the second secondary side winding 114 may be connected to the other terminal 196 (terminal "-" in this example) of the terminals of the transceiver's receiver port.

An impedance is connected between the first secondary side winding 113 and the second secondary side winding 114. More specifically, in this implementation, the resistor 106 is connected between a first end of the first secondary side winding and a first end of the second secondary side winding, and the resistor 107 is connected between a second end of the first secondary side winding and a second end of the second secondary side winding.

Typically, the first inductive coupling and the second inductive coupling are adapted to provide a first version of the transmit signal at the receiver port, and the impedance is adapted to provide a second version of the transmit signal at the receiver port. Also, generally, the purpose is that the second version of the transmit signal cancels the first version of the transmit signal. One way to achieve this is to provide a second version of the transmit signal having the same amplitude and opposite phase as the first version of the transmit signal.

In the implementation shown in fig. 1, the first inductive coupling 133 and the second inductive coupling 134 are non-inverting inductive couplings, and the resistors are coupled between transmitter ports and receiver ports having the same polarity (i.e., one resistor 106 is connected between the positive terminal "+" of the transmitter port and the positive terminal "+" of the receiver port, and the other resistor 107 is connected between the negative terminal "-" of the transmitter port and the negative terminal "-" of the receiver port). Thus, the phase effect of the first and second

inductive couplings

133, 134 on the transmit signal and the phase effect of the

impedances

106, 107 on the transmit signal have a modulo-2 pi phase difference (i.e., opposite phase) equal to pi for the periodic transmit signal.

The

impedances

106, 107 should preferably be chosen such that cancellation of transmit signal leakage to the receiver port is achieved and/or such that cancellation of receive signal leakage to the transmitter port is achieved. This may be achieved, for example, by selecting the

impedances

106, 107 such that the amplitude impact of the first inductive coupling 133 and the second inductive coupling 134 on the transmit signal is equal to the amplitude impact of the

impedances

106, 107 on the transmit signal.

Other example antenna interface apparatus for cancellation of transmit signals at a receiver port of a transceiver may be achieved by having both the first inductive coupling 133 and the second inductive coupling 134 be anti-phase inductive couplings in fig. 1.

In general, it should be noted that one or more of the antenna interface devices illustrated herein (e.g., the example antenna interface device 100 of fig. 1) may also provide cancellation of received signals at a transmitter port of a transceiver. In particular, the first inductive coupling may be further adapted to provide a first version of the received signal at the transmitter port, and the second inductive coupling and the impedance may be further adapted to provide a second version of the received signal at the transmitter port. Also, generally, the purpose is for the second version of the received signal to cancel the first version of the received signal. One way to accomplish this that one or more of the antenna interface devices illustrated herein implements is to provide a second version of the received signal that has the same amplitude and opposite phase as the first version of the received signal.

And typically (assuming that the antenna port is port 1, the transmitter port is port 2 and the receiver port is port 3, and assuming thatS12 represents the coupling from the transmitter to the antenna,S31 represents the coupling from the antenna to the receiver,S32 represents the coupling from the transmitter to the receiver andS23 represents coupling from receiver to transmitter), it should be noted that the separate transformers used in some embodiments herein allow sharing of the antenna between the transmitter and receiver (e.g., resulting in transformers with identical windings)S12=S31= -3dB coupling loss) in which the transmitter and receiver are magnetically connected by a transformer (e.g. of a transformer with identical windings)S32=S23= -6 dB). Isolation between the transmitter and receiver is obtainable by using appropriately connected resistors (or universal impedances). Since no resonance is introduced, the theoretical bandwidth is none when the inductors are magnetically coupledAnd (4) limiting.

If the

inductive couplings

133 and 134 are either both non-inverting or both inverting, the magnetic connection between the transmitter and receiver introduces a 180 ° phase rotation and isolation between the transmitter and receiver is obtainable by connecting resistors between the port terminals of the same polarity.

If one of the inductive couplings is non-inverting and the other inductive coupling is inverting, the magnetic connection between the transmitter and the receiver does not introduce a phase rotation, and isolation between the transmitter and the receiver is obtainable by connecting a resistor between port terminals of different polarity.

FIG. 2 schematically illustrates an example apparatus according to some embodiments.

Fig. 2 illustrates an example antenna interface apparatus for cancellation of transmit signals at a receiver port of a transceiver when connected to a differential port Transmitter (TX) 101, a differential port Receiver (RX) 104, and a differential port Antenna (ANT) 103 of the transceiver. For simplicity of representation, the boundaries of the antenna interface device (compared to 100 of fig. 1) and the transceiver ports (compared to 191, 192, 193, 194, 195, 196 of fig. 1) are omitted.

The antenna interface device includes an impedance (illustrated as two

resistors

206, 207 in fig. 2) and a distributed transformer. The distributed transformer has a primary side winding with a first portion 211 and a second portion 212, a first secondary side winding 213 and a second secondary side winding 214. The first secondary side winding 213 has a first inductive coupling 233 to the first part 211 of the primary side winding and the second secondary side winding 214 has a second inductive coupling 234 to the second part 212 of the primary side winding.

A first end of the first portion 211 of the primary side winding may be connected to one of the terminals of the antenna port of the transceiver (terminal "+" in this example), a second end of the first portion 211 of the primary side winding is connected to a first end of the second portion 212 of the primary side winding, and a second end of the second portion 212 of the primary side winding may be connected to the other one of the terminals of the antenna port of the transceiver (terminal "-" in this example).

A first end of the first secondary side winding 213 may be connected to one of terminals of a transmitter port of a transceiver (terminal "+" in this example), and a second end of the first secondary side winding 213 may be connected to the other of terminals of the transmitter port of the transceiver (terminal "-" in this example).

The first end of the second secondary side winding 214 may be connected to one of the terminals of the receiver port of the transceiver (terminal "+" in this example), and the second end of the second secondary side winding 214 may be connected to the other of the terminals of the receiver port of the transceiver (terminal "-" in this example).

An impedance is connected between the first secondary side winding 213 and the second secondary side winding 214. More specifically, in this implementation, the resistor 206 is connected between a first end of the first secondary side winding and a second end of the second secondary side winding, and the resistor 207 is connected between the second end of the first secondary side winding and the first end of the second secondary side winding.

In the implementation shown in fig. 2, the first inductive coupling 233 is a non-inverting inductive coupling, the second inductive coupling 234 is an inverting inductive coupling, and the resistors are coupled between transmitter ports and receiver ports of different polarities (i.e., one resistor 206 is connected between the positive terminal of the transmitter port "+" and the negative terminal of the receiver port "-", and the other resistor 207 is connected between the negative terminal of the transmitter port "-" and the positive terminal of the receiver port "+"). Thus, the phase effect of the first and second

inductive couplings

233, 234 on the transmit signal and the phase effect of the

impedances

206, 207 on the transmit signal have a modulo-2 π phase difference (i.e., opposite phase) for the periodic transmit signal equal to π.

The

impedances

206, 207 should preferably be chosen such that cancellation of transmit signal leakage to the receiver port is achieved and/or such that cancellation of receive signal leakage to the transmitter port is achieved. This may be achieved, for example, by selecting the

impedances

106, 107 such that the first inductive coupling 233 and the second inductive coupling 234 have an amplitude impact on the transmit signal that is equal to the amplitude impact of the

impedances

206, 207 on the transmit signal.

Other example antenna interface apparatus for cancellation of transmit signals at a receiver port of a transceiver may be implemented by having the first inductive coupling 233 be an inverting inductive coupling and the second inductive coupling 234 be a non-inverting inductive coupling in fig. 1.

FIG. 3 schematically illustrates an example apparatus according to some embodiments.

Fig. 3 illustrates an example antenna interface apparatus 300 for cancellation of a transmit signal at a receiver port of a transceiver. Example connections of the antenna interface apparatus to a Transmitter (TX) 301, a Receiver (RX) 304 and an Antenna (ANT) 303 of a transceiver are also shown.

The antenna interface apparatus 300 includes an impedance (illustrated as resistor 306 in fig. 3) and a distributed transformer. The distributed transformer has a primary side winding with a first portion 311 and a second portion 312, a first secondary side winding 313 and a second secondary side winding 314. The first secondary side winding 313 has a first inductive coupling 333 to the first part 311 of the primary side winding and the second secondary side winding 314 has a second inductive coupling 334 to the second part 312 of the primary side winding.

In the transceiver illustrated in fig. 3, the transmitter port, the receiver port, and the antenna port are single-ended ports.

A first end of the first part 311 of the primary side winding may be connected to an antenna port 391 of the transceiver, a second end of the first part 311 of the primary side winding is connected to a first end of the second part 312 of the primary side winding, and a second end of the second part 312 of the primary side winding may be connected to a reference potential (e.g. ground potential).

A first end of the first secondary side winding 313 may be connected to a transmitter port 393 of the transceiver and a second end of the first secondary side winding 313 may be connected to a reference potential (e.g., ground potential).

A first end of the second secondary side winding 314 may be connected to a receiver port 395 of the transceiver and a second end of the second secondary side winding 314 may be connected to a reference potential (e.g., ground potential).

Impedance 306 is connected between a first end of first secondary side winding 313 and a first end of second secondary side winding 314.

In the implementation shown in fig. 3, the first inductive coupling 333 and the second inductive coupling 334 are non-inverting inductive couplings. Thus, the effect of the first inductive coupling 333 and the second inductive coupling 334 on the phase of the transmit signal and the effect of the impedance 306 on the phase of the transmit signal have a modulo-2 π phase difference for the periodic transmit signal equal to π (i.e., opposite phase).

The impedance 306 should preferably be chosen such that cancellation of transmit signal leakage to the receiver port is achieved and/or such that cancellation of receive signal leakage to the transmitter port is achieved. This may be achieved, for example, by selecting the

impedances

106, 107 such that the first inductive coupling 333 and the second inductive coupling 334 have an equal effect on the amplitude of the transmit signal as the impedance 306 has on the amplitude of the transmit signal.

Other example antenna interface apparatus for cancellation of transmit signals at a receiver port of a transceiver may be implemented by having both the first inductive coupling 133 and the second inductive coupling 134 be anti-phase inductive couplings in fig. 3.

Part (a) of fig. 4 schematically illustrates an example apparatus after adjustment, according to some embodiments. The modified example antenna interface apparatus of portion (a) of fig. 4 is similar to the example antenna interface apparatus 100 illustrated in fig. 1, with the addition of one or

more circuit elements

421, 423, 424. Corresponding adjustments, i.e., adding one or more circuit elements, may be applied with respect to any of the other example antenna interface devices described herein (e.g., in fig. 2 or in fig. 3).

The adjusted example antenna interface apparatus of part (a) of fig. 4 is used for cancellation of a transmit signal at a receiver port of a transceiver. Example connections of the antenna interface apparatus to a Transmitter (TX) 401, a Receiver (RX) 404 and an Antenna (ANT) 403 of the transceiver are also shown.

Similar to fig. 1, the antenna interface device includes an impedance (illustrated as two resistors 406, 407) and a distributed transformer. The distributed transformer has a primary side winding with a first portion 411 and a second portion 412, a first secondary side winding 413 and a second secondary side winding 414. The first secondary side winding 413 has a first inductive coupling to a first part 411 of the primary side winding and the second secondary side winding 414 has a second inductive coupling to a second part 412 of the primary side winding. The impedance and distributed transformer are arranged in a similar manner to those of fig. 1.

The antenna interface device of part (a) of fig. 4 further includes one or more of a first circuit element (e.g., antenna port impedance 423), a second circuit element (e.g., transmitter port impedance 421), and a third circuit element (e.g., receiver port impedance 424).

As illustrated in part (a) of fig. 4, the first circuit element 423 may be connected in parallel to the

primary side windings

411, 412, the second circuit element 421 may be connected in parallel to the first secondary side winding 413, and the third circuit element 424 may be connected in parallel to the second secondary side winding 414.

In general, when referring to impedance herein, it is meant to include one or more of a purely real-valued impedance (resistance), a purely imaginary-valued impedance (capacitance or inductance), and any combination thereof in the form of a complex-valued impedance. Thus, any of the first, second and third circuit elements may comprise a real-valued part and/or an imaginary-valued part.

Any of the first, second and third circuit elements may be adapted to compensate for defects and/or impedance mismatch of the distributed transformer according to any suitable compensation method.

An antenna interface device in which one or more port impedances are added, as illustrated in part (a) of fig. 4, may be particularly useful when one or more of the transceiver ports are non-ideal. One or more of the port impedances may be tunable to accommodate impedance changes of one or more of the transceiver ports.

Part (b) of fig. 4 schematically illustrates an example apparatus according to some embodiments. The adjusted example antenna interface apparatus of portion (b) in fig. 4 is similar to the example antenna interface apparatus 100 illustrated in fig. 1, but shows impedance in a more general implementation. The corresponding generalization (i.e., converting one or more resistors to a complex-valued impedance) may be applied to any of the other example antenna interface devices described herein (e.g., in fig. 2, in fig. 3, or in part (a) of fig. 4).

The antenna interface apparatus of part (b) in fig. 4 is used for cancellation of a transmission signal at a receiver port of a transceiver. Also shown are example connections of the antenna interface device to a Transmitter (TX) 401, a Receiver (RX) 404 and an Antenna (ANT) 403 of the transceiver.

Similar to fig. 1, the antenna interface device includes an impedance (illustrated as two

impedances

408, 409; each including a real-valued and/or imaginary-valued part) and a distributed transformer. The distributed transformer has a primary side winding with a first portion 411 and a second portion 412, a first secondary side winding 413 and a second secondary side winding 414. The first secondary side winding 413 has a first inductive coupling to the first part 411 of the primary side winding and the second secondary side winding 414 has a second inductive coupling to the second part 412 of the primary side winding. The impedance and distributed transformer are arranged in a similar manner to those of fig. 1.

In addition to the conditions for selecting the impedance values described in relation to fig. 1, the complex-valued impedance in part (b) of fig. 4 may be adapted to compensate for defects and/or impedance mismatches of the distributed transformer according to any suitable compensation method.

In general, one or more of the size of the first portion of the primary side winding, the size of the second portion of the primary side winding, the size of the first secondary side winding, the size of the second secondary side winding, the impedance value (compared to 408, 409), and the circuit element value(s) (compared to 421, 423, 424) may be selected for matching the transmitter port impedance and/or the receiver port impedance and/or the antenna port impedance.

As applied in various embodiments herein, the distributed transformer may have any suitable ratio (e.g., ratio 1.

Fig. 5 schematically illustrates an example device 510 according to some embodiments. The device 510 may be, for example, a communication device. The apparatus includes a transceiver (TX/RX) 530 and an antenna interface device (AI) 500. The transceiver may be a full-duplex transceiver or a half-duplex transceiver. Alternatively or additionally, the transceiver may be a TDD transceiver. The antenna interface device 500 may be any of the antenna interface devices described in connection with fig. 1-4.

In general, the distributed transformers of the various embodiments presented herein may be implemented in any suitable manner. The distributed transformer may be an ideal transformer (coupling factor)k= 1) or non-ideal transformers (coupling factor)k<1, e.g.k= 0.85). Some loss may be caused by the use of non-ideal transformers and the phase shift may be imperfect (i.e., 0 ° or 180 °). However, the isolation and noise figure of the antenna interface device is determined primarily by the cancelling impedance, and remains relatively low even for non-ideal transformers.

Also, in general, each of the impedances and/or circuit elements illustrated herein may include real-valued and/or imaginary-valued portions, where appropriate (even though illustrated as purely resistive in any of the figures). For example, the impedance and/or circuit elements may be purely resistive, purely capacitive, purely inductive, or any combination thereof. Further, the impedances and/or circuit elements may be implemented using any suitable means (e.g., connecting resistor(s), capacitor(s), coil(s) in any parallel and/or series arrangement).

Generally, the cancelling impedances (106, 107, 206, 207, 306, 406, 407, 408, 409) may be selected based on (e.g., equal to, or absolute value equal to, corresponding to) the port impedances.

To accommodate the challenges caused by non-ideal transformers (and/or non-ideal impedances of transmitter/receiver/antenna ports), one or more reactive elements may be introduced in the antenna interface device (e.g., to achieve a desired cancellation phase difference). Fig. 4 represents an example of how this can be achieved.

One embodiment targeting a non-ideal transformer includes the

impedances

408, 409 illustrated in part (b) of fig. 4; each comprising a functional series connection of a resistance and an inductance.

One embodiment targeting non-ideal impedance of the transmitter port/receiver port/antenna port uses the apparatus illustrated in fig. 3 for impedance matching by sizing the windings of the transformer to achieve a desired matching of the transmitter port and the receiver port. For example, assuming that the antenna port experiences 50 Ω, the transmitter port experiences 30 Ω, and the receiver port experiences 70 Ω, the resistor 306 may be selected to be close to 30 Ω (e.g., 35 Ω) of the transmitter port, the first portion 311 and the second portion 312 of the primary side winding may be sized the same, the first secondary side winding 313 may be sized one third of the first portion 311 of the primary side winding, and the second secondary side winding 314 may be sized seven fifths of the second portion 312 of the primary side winding.

Embodiments may be present within an electronic device (such as a transceiver or a communications device) that includes apparatus, circuitry, and/or logic according to any of the embodiments described herein.

Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant art unless a different meaning is implied and/or expressly stated from the context in which the term is used.

Various embodiments have been referenced herein. However, those skilled in the art will recognize many variations to the described embodiments that will still fall within the scope of the claims.

It should be noted that in the description of the embodiments, the division of the functional blocks into specific units is in no way intended to be limiting. Rather, these partitions are merely examples. A functional block described herein as a unit may be divided into two or more units. Further, functional blocks described herein as being implemented as two or more units may be combined into fewer (e.g., a single) unit.

Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, where appropriate. Likewise, any advantage of any of the embodiments may apply to any other of the embodiments, and vice versa.

It is therefore to be understood that the details of the described embodiments are given by way of example only for the purpose of illustration and that all changes which come within the scope of the claims are intended to be embraced therein.

Claims

1. An antenna interface apparatus for cancellation of a transmit signal at a receiver port of a transceiver, the antenna interface apparatus comprising:

a distributed transformer having

A primary side winding connectable to an antenna port of the transceiver and having a first portion (111, 211, 311) and a second portion (112, 212, 312);

a first secondary side winding (113, 213, 313) connectable to a transmitter port of the transceiver and having a first inductive coupling to the first portion of the primary side winding; and

a second secondary side winding (114, 214, 314) connectable to the receiver port of the transceiver and having a second inductive coupling to the second portion of the primary side winding, wherein the first and second inductive couplings are adapted to provide a first version of the transmit signal at the receiver port; and

an impedance (106, 107, 206, 207, 306) connected between the first secondary side winding and the second secondary side winding, wherein the impedance is adapted to provide a second version of the transmit signal at the receiver port for cancelling the first version of the transmit signal.

2. The antenna interface apparatus of claim 1, wherein the antenna interface apparatus is also for cancellation of a receive signal at the transmitter port of the transceiver, wherein the first inductive coupling is further adapted to provide a first version of the receive signal at the transmitter port, and wherein the second inductive coupling and the impedance are further adapted to provide a second version of the receive signal at the transmitter port for cancellation of the first version of the receive signal.

3. The antenna interface device of any one of claims 1-2, wherein

A first end of the first portion of the primary side winding is connectable to the antenna port of the transceiver and a second end of the first portion of the primary side winding is connected to a first end of the second portion of the primary side winding;

a first end of the first secondary side winding is connected to the impedance and connectable to the transmitter port of the transceiver; and

a first end of the second secondary side winding is connected to the impedance and connectable to the receiver port of the transceiver.

4. The antenna interface apparatus of claim 3, wherein the transmitter port, the receiver port, and the antenna port are single-ended, and wherein a second end of the second portion of the primary side winding, a second end of the first secondary side winding, and a second end of the second secondary side winding are connectable to a reference potential.

5. The antenna interface apparatus of claim 4, wherein the first and second inductive couplings (333, 334) are non-inverting inductive couplings.

6. The antenna interface device of claim 3, wherein the transmitter port, the receiver port, and the antenna port are differential ports having a positive terminal and a negative terminal, and wherein a second end of the second portion of the primary side winding is connectable to the antenna port of the transceiver, a second end of the first secondary side winding is connectable to the transmitter port of the transceiver, and a second end of the second secondary side winding is connectable to the receiver port of the transceiver.

7. The antenna interface device of claim 6, wherein the first and second inductive couplings (133, 134) are non-inverting inductive couplings, and the impedance (106, 107) comprises a first impedance connectable between the positive terminal of the transmitter port and the positive terminal of the receiver port and a second impedance connectable between the negative terminal of the transmitter port and the negative terminal of the receiver port.

8. The antenna interface apparatus of claim 6, wherein one of the first and second inductive couplings (234) is an inverting inductive coupling, the other of the first and second inductive couplings (233) is a non-inverting inductive coupling, and the impedances (206, 207) include a first impedance connectable between the positive terminal of the transmitter port and the negative terminal of the receiver port and a second impedance connectable between the negative terminal of the transmitter port and the positive terminal of the receiver port.

9. The antenna interface device of any one of claims 1-8, wherein the impedance comprises a real-valued portion and/or an imaginary-valued portion.

10. The antenna interface apparatus of claim 9, wherein the impedance is adapted to compensate for imperfections and/or impedance mismatches of the distributed transformer.

11. The antenna interface device of any one of claims 1 to 10, further comprising one or more of:

a first circuit element connected in parallel to the primary side winding;

a second circuit element connected in parallel to the first secondary side winding; and

a third circuit element connected in parallel to the second secondary side winding;

wherein any of the first circuit element, the second circuit element and the third circuit element comprises a real-valued part and/or an imaginary-valued part and is adapted to compensate for defects and/or impedance mismatch of the distributed transformer.

12. The antenna interface device of any one of claims 1 to 11, wherein one or more of the size of the first portion of the primary side winding, the size of the second portion of the primary side winding, the size of the first secondary side winding, the size of the second secondary side winding, and the impedance are selected for matching of transmitter port impedance and/or receiver port impedance.

13. The antenna interface apparatus of any one of claims 1-12, wherein an amplitude effect of the impedance on the transmit signal is equal to an amplitude effect of a combination of the first inductive coupling and the second inductive coupling on the transmit signal.

14. The antenna interface apparatus of any one of claims 1 to 13, wherein a phase effect of the impedance on the transmit signal and a combined effect of the first inductive coupling and the second inductive coupling on the phase of the transmit signal have a modulo-2 pi phase difference equal to pi for a periodic transmit signal.

15. A transceiver comprising an antenna interface device according to any one of claims 1 to 14.

16. The transceiver of claim 15, wherein the transceiver is a full-duplex transceiver or a half-duplex transceiver.

17. The transceiver of any one of claims 15 to 16, wherein the transceiver is a time division duplex, TDD, transceiver.

18. A communication device comprising an antenna interface device according to any of claims 1 to 14 and/or a transceiver according to any of claims 15 to 17.